1. Field of the Invention
The present invention relates to a communication apparatus to which an external telephone can be connected, a communication method, and a storage medium storing a program.
2. Description of the Related Art
In recent years, in facsimile apparatuses, in order to reduce a facsimile function in size, reduce costs, and implement a common circuit adaptable to country-by-country postal, telegraph and telephone (PTT) standards, a data access arrangement (DAA), which is a semiconductor integrated circuit (IC), has been used for a telephone network controller.
Some apparatuses having a facsimile function, such as multifunction printer apparatuses, have a terminal to which an external telephone is connected, so as to share a telephone line with a telephone.
Japanese Patent Laid-Open No. 2005-57659 discloses a voltage detection system in which hook detection of an on-hook/off-hook state of an external telephone is performed by a DAA detecting a line direct-current voltage.
However, in the voltage detection system disclosed in Japanese Patent Laid-Open No. 2005-57659, when a certain variation in line direct-current voltage occurs even due to a cause other than line capture performed by the external telephone, the variation is falsely detected as an on-hook/off-hook state of the external telephone.